If you have any thoughts at all, you should be able to give a star rating. I think that's only fair. People have put their heart and soul into the track (or at least we hope) so if you have enough to say about their track one way or another, you can at least quantify it somewhat in stars. I have my own system for it. I give something 7 out of 7, then work back from there, giving and taking what I think. If I can't explain something, I give them back the point.